This invention relates to hand tools with foldout blades, and, more particularly, to such hand tools with multiple foldout locking blades.
Hand tools with multiple deployable blades have long been known and used in the home, in the workplace, and in sporting applications. A folding pocket knife having two blades is an example. The blades are carried inside a handle for storage, and are selectively opened, one at a time, when required to perform specific functions.
Pocket-knife-like devices, such as those produced by Wenger and Victorinox and commonly called xe2x80x9cSwiss Armyxe2x80x9d knives, use this same principle extended to a plurality of tools carried within the body of the knife on axles located at either end of the knife. Such implements typically incorporate a variety of types of blade-type tools, such as one or more sharpened blades, a screwdriver, an awl, a file, a bottle opener, a magnifying glass, etc. Generally, Swiss Army knives are designed to be sufficiently small and light for carrying in a pocket and are therefore limited as to the strength and robustness of their structure.
In recent years, devices known generically as xe2x80x9ccombination toolsxe2x80x9d have been developed and widely marketed. A combination tool is built around a jaw mechanism such as a full-size pliers head. The pliers head has handles fixed thereto. To make the combination tool compact yet capable of use in situations requiring the application of large forces, the handles are made deployable. To make the combination tool more useful, a number of blade tools, generally of the type found in the Swiss Army knife, are received in a folding manner within the handles themselves.
One useful feature of some conventional folding knives is the ability to positively lock the blade in the open position to prevent an unintentional closure during service that could cut the hand of the user. Lockbacks, sidelocks, axle locks, and other types of locks are known in the art. Another useful feature is the biasing of the blade toward its closed position from angular orientations close to the closed position. Such a biasing acts as a detent to prevent the blade from unintentionally folding open when carried or when another blade is already open and in use. The blade may also be biased toward its open position from angular orientations close to the open position. In either case, the biasing effect gives a secure feel to the closing and opening of the blades. Cam, backspring, ball detent, and other types of biasing structures are known in the art.
Positive locks used in conjunction with biasing structures are desirable features of knives, but they have not been successfully utilized in knives having multiple blades rotating in the same direction on a common axle. (When the term xe2x80x9cbladexe2x80x9d or xe2x80x9cblade toolxe2x80x9d is used herein in reference to deployable tools received into the handle of the combination tool, knife, or other type of tool, it refers to any relatively thin tool that is folded into the handle, regardless of the utilization of the tool. Such a xe2x80x9cbladexe2x80x9d therefore includes, but is not limited to, a sharpened knife blade, a serrated blade, a screwdriver, an awl, a bottle opener, a can opener, a saw, a file, etc.) Existing approaches have internal structures that require too much space when adapted for use on several side-by-side blades, or the locking release controls take up too much space or are inconvenient. For example, a typical combination tool has four or more blades folding from a common axle in each handle, where the width of the handlexe2x80x94the required envelope size within which the entire structure must fitxe2x80x94is on the order of about 1 inch or less. The sides of the handle, the blades, and any locking and biasing mechanism must fit within that width, and the externally accessible lock releasing structure must also fit on the outside of the handle within that width. If the width of the handle of the hand tool is increased significantly above about 1 inch, the combination tool will no longer be comfortable in the hand. There have been some attempts to provide a positive lock for the blades of a combination tool, but they have been highly inconvenient to use in practice.
There is a need for an approach to locking and biasing multiple, side-by-side blades of combination tools, knives, and other types of hand tools where the blades pivot on a common axis. The present invention fulfills this need, and further provides related advantages.
The present invention provides a hand tool wherein multiple blades pivot on a single axle. The blades are each positively locked into their open positions by a single strong locking mechanism. The blades are also biased toward their closed positions and their open positions. When one blade is opened, the others stay in their closed positions. The opened blade is positively locked and later unlocked without moving the other blades from their closed positions. The locking and biasing mechanism fits within the envelope size required for a hand tool, and has been demonstrated operable for four blades within a space of less than 1 inch width.
In accordance with the invention, a hand tool comprises a tool body having a pair of oppositely disposed sides, an axle extending transversely between the sides of the body at one end of the tool body, and at least two blades supported on the axle. Each blade includes a blade base having a peripheral surface and an implement extending outwardly from the blade base, and further has a bore through the blade base with the axle extending through the bore so that the blade base and thence the blade is rotatable on the axle between a closed position wherein the blade is contained within the tool body and an open position wherein the blade extends from the tool body. There is a notch in the peripheral surface of the blade base. A single rocker is supported on the tool body and has a locking finger extending therefrom. The locking finger is dimensioned and positioned to engage the notch of each blade base when the blade is in the open position. A biasing spring reacts against the single rocker in a direction so as to force the locking finger against the peripheral surface of the blade base.
There is, additionally, means for biasing one of the blades toward the open position while biasing all others of the blades toward the closed position. This biasing means preferably takes the form of a first cam surface on the peripheral surface of each blade base at a location adjacent to the notch, having a first cam maximum surface height and a first cam maximum surface height angular position, and a second cam surface on the peripheral surface of the blade base at a location remote from the notch, having a second cam surface height less than the first cam surface height and a second cam maximum surface height angular position located about 110 to about 120 degrees from the first cam maximum surface height angular position. The first cam maximum surface height is preferably slightly smaller than the second cam maximum surface height.
Thus, the invention provides a locking/biasing mechanism that positively locks any one of the blades into its open position while biasing the remaining blades toward their closed positions. The locking mechanism has a single release that releases the blade that is locked into the open position. As the selected blade is opened or closed against its biasing force, the other blades remain in their closed positions under the influence of their biasing forces. Subsequently, a different blade may be selected for opening, with the same results and performance.
Other features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention. The scope of the invention is not, however, limited to this preferred embodiment.